CH. 3 ~ CELLS

Robert Hooke 1665 Looked at thin slices of cork under a microscope Did not know at the time about their structure and function. What IS a cell?

1670’s Van Leeuwenhoek….hand lens A cell is the smallest unit of life that can carry out all the activities necessary for life.

THE CELL THEORY One of the foundations of modern biology. It states: All living things are made up of one or more cells Cells are the most basic unit of structure and function in an organism Cells originate only from pre-existing cells 4. Energy Flow (metabolism) occurs within cells; must maintain an internal balance (homeostasis) 5. Cells contain DNA (hereditary information) -reproduce. Schleiden + Schwann + Virchow

VIRCHOW “Omnis cellula e cellula” 1855: New cells arise from pre-existing cells Tremendous controversy….against the prevailing theory at the time “Spontaneous Generation” aka Vitalism Ponds dry up…..teeming with life again Rotting meats ‘spontaneously’ give rise to maggots

“Spontaneous Generation” (Life evolves from non-life) (Francesco Redi 1688)

Spallanzani 1700’S Still did not believe….Blocking the “vital force”….. Who ultimately disproved spontaneous generation?

PASTEUR 1860’S

TYPES OF CELLS

Cell Size 1 meter = 1000 millimeters (mm) 1 mm = 1000 micrometers (um) 1 um = 1000 nanometers (nm) Cell Size

Why are cells so different? Specialized Functions! 1m

What Limits the Size of a Cell? Human Body consists of about 100 trillion cells (A string 100 trillion inches long could be wrapped around Earth more than 63,000 times) Cell grows- needs to take in food and get rid of waste through the cell membrane. Cell cannot grow so large that their surface area becomes too small to take in enough food and remove enough wastes Cells volume increases faster than its surface area. Surface area = 6s2 Volume = l x w x h

DEFINITIONS/DESCRIPTION PROKARYOTIC CELL EUKARYOTIC CELL SIZE Very small .2-10 um Varies, generally much larger 5-100 um ORGANISMS Bacteria, cyanobacteria Plants, animals and fungi CILIA AND FLAGELLA Yes (pili) Yes CELL WALL Yes (Plants and Fungi) No (Animals) PLAMA (CELL) MEMBRANE CYTOPLASM CHROMOSOMES, DNA Strand of DNA (nuceloid,plasmid) RIBOSOMES MEMBRANE BOUND ORGANELLES No

Every bacterial cell Eubacteria Archeabacteria Every organisms that is not bacteria: Animals – Plants – Fungus - Protists

Inner Life of the Cell Animation 3.12

Cell Membrane Surrounds ALL cells Semi-permeable – only allows certain substances to pass through Contains proteins that help to pass materials through. “Phospholipid bilayer” Flexible and “fluid”

Cytosol/Cytoplasm Fluid inside the cell that contains the organelles and allows reaction to occur Composed mostly of water and plays a role in diffusion of materials across the cell membrane.

Nucleus Membrane-bound organelle Found only in Eukaryotes Controls the cell functions and processes Contains DNA that directs the formation of necessary proteins. (genetic blueprint)

Nucleolus An organelle within the nucleus that produces ribosomes and RNA

Ribosomes small organelles that are sites of protein synthesis Take information from the DNA (delivered to the ribosome by RNA) and use it to make protein Sometimes found on the ER (or the rough endoplasmic reticulum), but also found in the cytoplasm of ALL cells

Endoplasmic reticulum (ER) – Endoplasmic reticulum (ER) – detoxification and transport. Attached to the nuclear membrane and zigzags through the cell Rough or smooth Rough = has ribosomes Smooth = no ribosomes

Golgi Apparatus (Bodies) Packaging and distribution Flattened, layered, sac-like organelles which are located near the nucleus. Works w/ ER….

MITOCHONDRIA “Powerhouse” of the cell Converts food into energy (ATP) Inner and outer membrane Has it’s own DNA (endosymbiotic theory) Found in Eukaryotes only Found in both plants and animals

VACUOLE Contains water (Can also store nutrients, waste products) Large in plants, small in animals Controls “turgor pressure” in plants.

Lysosomes Contain enzymes to break down old organelles or kill the cell. Centrioles only in animals cells. Make the spindle for cell reproduction

Flagella – long whip-like tail for movement Cilia – short hairs for movement

T R A N S P O lysosome ER and Golgi

PLANT CELL

CHLOROPLASTS Converts sunlight, water and carbon dioxide to sugar and oxygen through photosynthesis Has chlorophyll – pigment that captures the sun’s light. Inner and outer membrane Found in Eukaryotes only Found only in plants (producers/autotrophs)

Cell Wall A rigid structure found on the outside of plant, fungal and bacterial cells Permeable – allows most substances to enter freely Composed of cellulose and protein Located OUTSIDE of the cell membrane Structure relates to function: The rigid structure of the cell wall provides support and structure for the organisms

Animal Plant No cell wall No chloroplast Small vacuoles Has centrioles Cell wall Chloroplasts Large vacuole No centrioles

What Limits the Size of a Cell? Intro to Cell Size Lab……… What Limits the Size of a Cell? Human Body consists of about 100 trillion cells (A string 100 trillion inches long could be wrapped around Earth more than 63,000 times) Cell grows- needs to take in food and get rid of waste through the cell membrane. Cell cannot grow so large that their surface area becomes too small to take in enough food and remove enough wastes Cells volume increases faster than its surface area. Surface area = 6s2 Volume = l x w x h

Passive Transport: 1. Diffusion – movement of molecules from an area of high concentration to an area of lower concentration. Demos: Dye in Water Sugar Cube *PE vs KE Particles have…..

Concentration gradient (High to low) Equilibrium KE Solute Solvent P/S Diffusion; passive Concentration gradient (High to low) Equilibrium KE Solute Solvent Solution